Identification of a genetic subcluster of HIV type 1 subtype C (C') widespread in Ethiopia.

Others and we have previously shown that subtype C is the predominant HIV-1 subtype and the major cause of AIDS in Ethiopia. The present study shows that subtype C in Ethiopia has a genetic subcluster, designated C', has not increased in frequency, or spread geographically, over the period 1988 (%C' = 23/53) to 1996-1997 (%C' = 26/50). There is no association of the HIV-1 subtype C or subcluster C' with geographic location, time of sample collection, or risk group in Ethiopia. Of 105 randomly collected samples representing 7 different towns in Ethiopia, all but 2 (1 subtype A from Addis Ababa, 1997 and 1 subtype D from Dessie, 1996) belong to subtype C.